1. Field of the Invention
The present invention relates to a disk cartridge for receiving an information recording and/or reproducing medium such as a disk and a disk drive apparatus for recording and/or reproducing information on/from the disk, and more particularly, to a disk cartridge and disk drive apparatus having an improved identification device which identifies the kind of disk in the disk cartridge.
2. Description of the Related Art
Recently, disk cartridges, which receive recording and/or reproducing media such as optical disks or magneto-optical disks to be used in a disk drive, are widely used as recording and/or reproducing apparatuses which reproduce images and sound data. Various types of disk cartridges with improved recording density have been manufactured according to development of multimedia and requirements for disk cartridges having a large capacity. For example, various types of disk cartridges for DVD-RAM are provided with different recording densities. Examples of the disk cartridges include an ordinary single-sided disk for recording information on one side of the disk, a double-sided disk for recording information on the front and rear sides of the disk, a single-sided disk with double recording layers for constituting a two-fold recording layer on one side to record information on each layer, a double-sided disk with double recording layers for applying the single-sided disk with double recording layers to the front and rear sides, and a single-sided disk having narrow track pitches.
As the recording density changes, the methods for recording and reproduction used in a disk drive apparatus also change. For example, the methods for recording and reproducing information in the disk drive apparatus vary according to the formation of track pitches and recording layers on the disk. Consequently, a structure for identifying the types of the disk cartridges when the disk cartridges are mounted in the disk drive is required.
A conventional structure for identifying the types of the disks, shown in FIG. 1, is disclosed in Japanese Patent Publication No. 11-120733. Referring to FIG. 1, an identification magnet 5, which is used to identify the disk type, is installed on a disk cartridge 1 which receives a disk 2 in a case 3. A magnetic sensor 7 is installed in a disk drive apparatus 6 to detect the identification magnet 5. When the disk cartridge 1 is mounted in the disk drive apparatus 6, the magnetic sensor 7 detects the magnetic field of the identification magnet 5 to determine the kind of the disk cartridge 1, which is shown as a large capacity disk cartridge. The magnetic sensor 7 transfers the result to a controller (not shown) of the disk drive apparatus 6 to perform an operation according to the kind of the disk cartridge. The identification magnet 5 is not installed on a small capacity disk cartridge. In this case, the magnetic field is not detected by the magnetic sensor 7 when the small capacity disk cartridge is mounted in the disk drive apparatus 6, thereby the kind of the mounted disk cartridge is identified as a small capacity disk cartridge. Thus, the conventional method identifies the kind of the disk cartridges by setting the magnetic sensor 7 on/off according to the existence of the identification magnet 5. Consequently, the conventional method identifies only two kinds of the disk cartridges such as large capacity and small capacity cartridges.
When the conventional method is used to identify various kinds of disk cartridges, the number of magnets 5 is varied according to the number of the kinds of disk cartridges. A plurality of the magnetic sensors 7 are installed to detect the maximum number of installed magnets 5. The kinds of disk cartridges are thus identified based on the number of the magnetic sensors 7.
According to another method, the magnetic field of the magnet 5 is varied according to the kinds of the disk cartridges. However, this requires a delicate circuit in the magnetic sensor 7 to distinguish the intensity of the magnetic field of the identification magnet 5.
However, increasing the numbers of the magnets and the magnetic sensors leads to an increase in the size and weight of a disk drive along with an increase in the manufacturing and production costs. Also, by varying the intensity of the magnetic field of the identification magnet, in addition to the need for a delicate identifying circuit, as the magnetic field deteriorates, the magnet cause an erroneous identification of the kinds of the disk cartridges. As a result, novel and simple structures for disk cartridges and disk drive apparatuses to identify various kinds of disk cartridges are required.